System temperature really hot

I’ve tried the module mm-system-temperature to display the raspberry temperature , it works fine except the temperature is around 73-80 degrees celcius (163-176 fahrenheit) , my living room is around 25 degrees.

That sounds about what my rpi was doing. Mine was closer to 65-70 °C. Then I bought this case and now it’s consistently sitting around 45-50 °C. Even with processor intensive tasks, it rarely hits 60°C.

My fan is quiet, but remember that these are cheap fans. You may get a very noisy one. Fans are cheap, you can buy a bunch of them and figure out which is the quietest. Or you can find some really quiet ones through an electronics vendor such as DigiKey or Mouser, and pay a higher price for them. I replaced two 30mm square, very noisy fans on my 3D printer, $7 each at the time. Now they’re a little over $9. Good fans are expensive.